1. Field of the Invention
The present invention relates to a display control apparatus which includes a flat panel display unit (FDP) such as a plasma display unit as a standard I/O device and can be arbitrarily connected to a CRT display unit, and can be suitable for use in a computer system such as a personal computer and a personal workstation.
2. Description of the Related Art
Liquid crystal displays and plasma displays have been used as display units for conventional lap-top type personal computers and personal workstations. However, strong demand has arisen for running an application program created for a CRT display unit in the above computer so as to utilize a wealth of all previous software. For this reason, the above computer equipped with a plasma display unit as a standard I/O device is arranged to be connectable to a CRT display unit as an optional I/O device.
A CRT display unit multigradation palette (CRT palette) is different from a plasma display unit gradation designation (4 through 16 gradation levels) palette (PDP palette), and different palette values are set therein.
For this reason, when a CRT application program runs to dynamically update the CRT palette, the palette value of the PDP palette is not changed even if the CRT palette value is changed.
Similarly, in a system to which a CRT color display unit can be arbitrarily connected, different palette values are set in a color palette for designating display colors of the CRT color display unit and the PDP palette. Even if the palette value of the CRT palette is arbitrarily changed in accordance with a display color designated by CRT application software, the palette value of the PDP palette is not changed. For this reason, although a change in gradation or hue can be identified on the CRT display screen, the change cannot be reflected on the PDP, resulting in inconvenience.